Conventionally, a vehicle system automatically stops an internal combustion engine when a predetermined stop condition is satisfied while a vehicle travels. Specifically, a known idle stop system stops injection of fuel from a fuel injection valve to automatically stop an internal combustion engine when a vehicle speed of a vehicle becomes zero and the vehicle stops. It is noted that even when a vehicle stops and an internal combustion engine turns to an idle stop condition, the internal combustion engine in an idle stop condition may be immediately started to start the vehicle due to a stop condition caused by a halt point (temporary stop) on the road or change of a state of a traffic signal. In general, it is considered that fuel consumption may not be reduced unless the internal combustion engine is stopped for more than a predetermined period such as 5 seconds when performing such an idle stop. Therefore, when an idle stop time period is short, fuel consumption may be increased contrary.
For example, when a vehicle repeats traveling on the same path such as a commutation route, a stop period of the vehicle is considered short when the vehicle stops. For example, JP-A-2004-132333 discloses an art to beforehand configure a navigation device to prohibit idle stop in such an area thereby to avoid unnecessary idle stop. JP-A-2004-132333 further exemplifies an art to prohibit idle stop according to an assigned area in which idle stop is prohibited in accordance with a personal tendency. It is noted that in the art of JP-A-2004-132333, a user needs to beforehand assign an area in which idle stop is prohibited. Consequently, operation of the device is complicated. In addition, such an area, in which idle stop is prohibited, may include a stop point at which an actual stop period is long sufficiently to reduce fuel consumption by idle stop. As described above, when idle stop is uniformly prohibited, a fuel consumption reduction effect may not be appropriately caused by idle stop.